The invention relates to a method and system for remote monitoring of groundwater. In particular, the invention relates to remote monitoring of a pump and treat method at a remediation site.
Contaminants from a pollutant source can contact a groundwater aquifer to form a groundwater contaminant plume. The plume can migrate in the direction of groundwater flow. A pump and treat method can be used to provide remediation of the plume-containing aquifer. Pump and treat operates by intercepting the groundwater at a capture zone, pumping the groundwater from the capture zone to the surface, removing the contaminant in a surface remediation unit and then either recharging the treated water back into the ground or discharging it to a surface water body or municipal sewage plant. Once the groundwater has been pumped to the surface, contaminants can be removed to very low levels with established remediation technologies or combinations of established technologies. Examples of commonly applied surface remediation technologies include air stripping, carbon adsorption, oil-water separation, chemical oxidation, membrane filtration, metals precipitation/adsorption and ion exchange.
Pump and treat is an accepted remediation technology however it involves high equipment and labor costs. Efforts to improve pump and treat have focused on control in two distinct phasesxe2x80x94an in situ phase during migration to or at the capture zone and the remediation phase after pumping to the surface. The two phases involve different considerations. It would be advantageous to closely monitor a pump and treat system to assure process effectiveness and regulatory compliance. Further it would be advantageous to provide monitoring that would assure that cost saving from effective monitoring was not dissipated by the cost of monitoring itself. Thus far, effective pump and treat system monitoring has been limited to control of the first in situ phase. For example, Misquitta, U.S. Pat. No. 5,639,380 discloses monitoring an extraction well for the purpose of controlling groundwater hydrodynamics. In the Misquitta process, groundwater is extracted from a well at a first flow rate, hydrodynamics of the surrounding area are monitored and the hydrodynamic information is transmitted to a computer controller, which computes a new second flow rate and automatically adjusts a pump to the second flow rate to maintain a desired capture zone. Similarly, Dawson, U.S. Pat. No. 5,316,085 discloses providing liquid level sensing means within a wellbore. A pump controls the liquid level in response to the sensing means. Lowry et al., U.S. Pat. No. 6,098,448 discloses determining permeability, i.e. soil conductivity to fluid flow.
These monitoring patents are limited to sensing water pressure or hydrodynamics in the vicinity of a well for the purpose of adjusting flow. While this is an important consideration in controlling a pump and treat system, equally if not more important considerations relate to control of the surface treatment step. Control of the surface treatment step may depend on the nature and extent of the contaminant in either or both of the feed groundwater from the capture zone and product water from the treatment facility. Detection of the nature and extent of a contaminant depends upon timely testing of representative samples and the ability of a sampling system to representatively capture the contaminant of interest.
Conventional remediation site monitoring, diagnostics, and reporting are expensive and labor intensive operations. Yearly costs for remediation site monitoring, diagnosing and reporting often exceed over $2000 per well. Conventional remediation site monitoring, diagnosing and reporting methods and systems comprise providing a well or other access means for groundwater at a remediation site. A person visits the remediation site, locates the well, and accesses the well. The groundwater in the well is sampled for characteristics (hereinafter xe2x80x9cgroundwater characteristicsxe2x80x9d), such as, but not limited to, water quality parameters; groundwater level; and contaminants such as benzene, toluene, ethyl-benzene, xylenes (BTEX), aromatic hydrocarbons and chlorinated solvents such as trichloroethylene (TCE), tetrachloroethylene (PCE) and their degradation products, dichloroethylene and vinyl chloride in the groundwater. The groundwater sample is then transported to a laboratory, often remote from the remediation site. The sample is then analyzed for certain characteristics by appropriate methods. Costs are associated with each step and the costs are often high depending on the well""s location with respect to the laboratory. Exact costs are remediation site dependent, reflecting a complexity of an analysis to be performed. Real-time data for the groundwater is desirable. The transportation of the sample from the well to the laboratory takes time. Further, time delays are associated with the analysis of the groundwater sample.
There is a need first, for monitoring, diagnosing and reporting properties of effluents to or from a pump and treat treatment zone and second, for a system and process to accurately sample the effluents of a pump and treat process and system.
The present invention provides a method and system to monitor a groundwater pump and treat system and to use the information acquired by the monitoring to control the system. In the method, a contaminated aqueous composition is withdrawn from a groundwater extraction well and the groundwater is treated in a pump and treat system to remove a contaminant. The treating of the aqueous composition is monitored from a location remote from the groundwater extraction well and the treating is adjusted to remove a contaminant in accordance with the monitoring.
In another embodiment, the invention relates to a system to treat a contaminated aqueous composition. The system comprises a capture zone to intercept a contaminated aqueous composition and a surface pump and treat system to receive and treat the contaminated aqueous composition from the capture zone. The system also includes a sensor that senses a contaminant in the contaminated aqueous composition and a monitor to receive information concerning the contaminant from the sensor and to consequently control the pump and treat system to treat the contaminated aqueous composition. The monitor is situated at a location remote from the pump and treat system.